Automatic brake adjuster



Patented Oct. 24, 1950 UNITED STATES PATENT o.1=i-"1c1:fl

AUTOMATIC BRAKE. ADJ USTER Vernon M; Schuster, Alexandria, Minn. l Application-JanuaryvZS, 1947, Serial No. 724,867-

2 Claims. l

My invention relates to brakes, and more particularly to automobile brake adjusters.

The object of my invention is to provide an automobile brake adjuster adapted to adjust the brakes 'of an automobile automatically for any wear of the brake lining or the like and to eliminate the expensive manual adjustments by mechanics caused by wearing of the brake parts.

Another object of my invention is to provide an automatic brakeadjuster consisting of a minimumof parts, of which only a few movev at all and then only a fraction of an. inch; thereby assuring a longlifeto ther adjuster and eliminating replacements of worn parts:

Other'objects of my invention may appear in the following specification describing my invention with reference tothe accompanying drawings-illustrating av preferred embodiment of my invention.

It is, however, to be understood that my invention is not to be limited or restricted to the exact construction andY combination of parts described in the specication and shown in the drawings, but that such changes and modifications can be made which fall within the scope of the claims appended hereto.

In the drawings:

Figure 1 is a fragmentary plan view of an automobile brake equipped with the automatic brake adjuster according to my invention.

Figure 2 is a sectional view taken on line 2-2 in Figure 1.

Figure 3 is a sectional view taken on line 3-3 in Figure 1.

Referring now in detail to the drawings, the automatic brake adjuster according to my invention has a hollow cylindrical -body l0, resting on a base Il, to which it is fastened in any conventional manner, and which in turn is secured to the bottom I2 of a brake band plate.

This brake drum is of conventional construction and contains a hydraulic wheel cylinder 13, to the piston rods I4 whereof the brake shoes I5 are pivotally secured in the conventional manner. A retractor spring IB extends between and is secured to the brake shoes |5 to return them into inoperative position ywhen the brake pressure in the cylinder I3 is released.

In the hollow cylindrical body I0, two substantially round adjusting bars are slidably arranged, and between them a helical spring I 8 is located urging the adjusting bars I'I outwardly in relation to the cylindrical body I0.

The outer end I8 of each adjusting bar I1 is attened and adapted to engage a notch I9 pro.

Shoe I5.

The upperportionofeach'adjusting bar: is`

provided with a set'of ratchet teethfZwhi-ch are arranged so thattheY vertical stopesurfaoeY ofeach ratchet tooth. faces inwardly; i. e., towards' the center of the cylindrical body Ill.`

At a distance from each endV of the cylindrical! body I0, a rectangular opening 2-;|:is provided :in: the upper'portion of said; bodyy IU uncovering some ofthe ratchet teeth 2B in the adjusting y bar I1.

In each opening 2| in thebody lilealockkey; or ratchet dog 22 is arranged which issomewhatf shorter than the corresponding-opening;ZIE andy provided on its inner surfacenwithtwo*l ratchet#` teeth 23` arranged so that they engage. teethf20 on the adjustment bars I1 one. 'ata time.

A rectangular cover 24 has. avdownwardlyeX-r tendingl circumferential` flange 25'iitting onto,the.= top portion of 'the body It.' A curyed:1eaf,..or bladev spring 26 is arranged; underA the. topf ofntheg.I coverr24 sothat the ends., offsaid; springv 2B.. ener.

When the brakes are applied and the brake l shoes I5 move outwardly to engage the brake drum, the helical spring I8 urges the top adjustment bars I 'I outwardly so that they remain in en gagement with the notches I9 in the brake shoes I5. This movement of the adjustment bars Il is imparted also to the lock keys or ratchet dogs 22 so that they move outwardly until they contact the outer edges of the rectangular openings 2l in the body. If the outward movement of the brake shoes should continue, the helical spring I8 forces the adjusting bars I1 to slide under the lock keys or ratchet dogs 22. When the brakes are released, the retractor spring lo withdraws the brake shoes I5 away from the brake drum and thereby forces the adjusting bars I1 inwardly of the body I, but only to positions in which the ends of lock keys or ratchet dogs 22, 22 abut the inner ends of the openings 2|, 2|. The ratchet dogs thereby limit the inward movement ofthe adjusting bars and of the brake Shoes l5 to amounts equal to the dif- 3 ferences in length between the ratchet dogs 22, 22 and the openings 2I.

As the brake lining wears down, the helical spring I8 pushes the adjusting bars I1 further out of the body so that the brake adjustment is made automatically for the life of the brake lining.

Turning the screw 21 in one direction acts to atten the bowed leaf spring 26 and thereby increase the tension thereof upon the ratchet dogs 22, 22, whereby wear in the ratchet teeth of the dogs and of the bars I1, I1 is compensated for, and lost motion in the operation of the ratchet bars I1, I1 and ratchet dogs 22, 22 is eliminated, whereby more accurate and reliable operation of the device under service conditions is assured. Adjusting the screw 21 in the opposite direction relaxes the spring 26 from an overly compressed condition and permits procuring normal operative engagement of the ratchet dogs 22 with the adjusting bars I1.

Having described my invention, I claim as new and desire to secure by Letters Patent:

1. An automatic brake adjuster comprising a tubular body, a pair of opposed ratchet bars arranged to slide endwise in said body, expanding spring means between and urging said ratchet bars outwardly of the opposite ends of said body, said body being formed on its sidewall with longitudinal openings exposing portions of said ratchet bars, ratchet dogs positioned in said openings and confined therein for:y

radial movement relative to said body and for longitudinal movement relative to said body, said openings being slightly longer than said ratchet dogs whereby limited movement of said ratchet dogs along said body is provided for, and spring means' yieldably urging said ratchet dogs radially inwardly into engagement with said ratchet, bars, said spring means comprising a longitudinally arranged leaf spring having its opposite ends engaged with said ratchet dogs, said leaf .spring being bowed away from the side intermediate '1 4 of said body, and means mounting said leaf spring on said body comprising adjusting means for flattening said leaf spring in a manner to increase the tension of said leaf spring to increase the force of engagement of said ratchet dogs with the ratchet bars.

2. In an automatic adjuster for a brake involving a pair of opposed shoes mounted for movement away from each other on a brake drum shield for applying the brake, a tubular body mounted on said brake drum shield between said shoes, ratchet bars slidable conned in opposite ends of said body and projecting therefrom into engagement with related shoes, expanding spring means urging said ratchet bars outwardly away from each other, ratchet dogs, means on said body mounting said dogs for limited longitudinal and radial movements relative to said body, positioning spring means on said body engaging both of said ratchet dogs and yieldably urging said ratchet dogs in a radially inward direction into engagement with said ratchet bars, means conning said positioning spring means in place on said body, and adjusting means on the last mentioned means for adjusting the tension of said positioning spring means.

VERNON M. SCHUSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,644,378 Hirschler Oct. 4, 1927 2,002,139 Des Rosiers May 21, 1935 2,057,749 Tatter Oct. 20, 1936 2,154,082 Baker Apr. 11, 1939 2,175,446 Rasmussen et al. Oct. l0, 1939 2,229,919 Dimont Jan. 28, 1941 2,345,062 Nachtwey Mar. 28, 1944: 

